The present invention relates to an armature of an electric rotating machine, or more in particular to an armature of an electric rotating machine comprising an armature core axially divided into a plurality of members, in which a plurality of armature coil sides are contained in each slot of a member, which coil sides are divided into at least two parts and contained in different slots in other members.
Armatures of electric rotating machines of this type are disclosed in U.S. Pat. No. 4,341,971 and France Pat. No. 962,825. In view of the fact that the reactance voltage induced at each coil at the time of commutation and the commutation electromotive force generated in the commutating pole for cancelling the reactance voltage are varied with coils, thus making a satisfactory commutation unobtainable, the armature of U.S. Pat. No. 4,341,971 comprises a structure of each coil side arranged to attain a uniform mutual induction with an adjacent coil in order to equalize the reactance voltage and the commutation electromotive force of each coil. However, no consideration is given to the mutual induction of a coil end with an adjacent coil end, but the form and position of each coil end is determined primarily in a way convenient for fabrication of the armature.
A construction of a coil end conventionally employed by the present applicants will be explained with reference to FIGS. 1 and 2. An armature core 9 is divided axially into a pair of members 9a, 9b having slots 11a, 11b respectively containing armature coils 12. In the first step of the electrical working of these coils, a conductor strand is formed into a predetermined shape in a die and is subjected to insulation. In order to facilitate the insertion of the coil into a slot, the coil ends on commutator side and opposite side, of the coil sides 12a.sub.1, 12c.sub.1 and 12b.sub.1, 12d.sub.1 contained in the same slot of the core member 9a distant from the commutator 13 are integrally fixed by being wound with armored insulating tape or the like. It is common practice to integrate a plurality of coils in the same slot to facilitate coil insertion into slots for an improved workability.
In an armature having the above-mentioned structure, the reactance voltage and the commutation electromotive force are equalized to some degree as mentioned above, resulting an improved commutation performance. Nevertheless, the commutation performance is still unsatisfactory even after various considerations of the relation between the armature windings and armature core. Unavoidably, the commutation performance in the prior art is thus the best available compromise obtainable.